In various applications it is required to store, digitize and/or display fast transient electronic signals. One example is found in storage-type oscilloscopes which store and display transient signals by depositing a trace of charge on a mesh in a cathode ray tube; the charged mesh is then used to modulate a flood of electrons impinging onto the CRT screen. Another example of importance in signal analysis systems is the conversion of analog signals to digital representations, which can then be stored and manipulated by conventional digital processing. Typically the analog signal is converted to a digital equivalent by means of conventional analog-to-digital (A/D) converters. This approach is costly when wide bandwidth analog signals are to be processed.
Another device for storing analog signals is known in which the samples of the analog signal are gated onto a number of storage capacitors, and subsequently gated out from the storage capacitors to provide a desired output signal representative of the input signal. A difficulty with this prior art device is that all of the storage capacitors are connected to a common output line, which itself has a large distributed capacitance. Thus, when the charge from any particular storage capacitor is dumped onto the common output line, the resulting output voltage is significantly diminished from the original input voltage which charged that capacitor. The system signal-to-noise ratio is thereby degraded. To overcome this problem, it would be necessary to increase the capacitance of the storage capacitors relative to the distributed capacitance of the output line. This solution is not acceptable for high-speed devices, since the maximum possible write-in speed would then be limited by the large time constant of the signal source output resistance and the individual storage capacitors.